part of preceded by NF stage 60 NF stage 61 XAO:1000073 Nieuwkoop and Faber stage 61, corresponding to a tadpole of age about 48 days at 22-24 Celsius and having the following external morphological criteria: Head narrower. Tentacles considerably shortened, mostly curved backwards. Length of n. olfactorius equal to diameter of bulbus olfactorius. 4th arterial arch seen just in front of adult skin area of forelimb. Openings of gill chambers considerably narrowed. Forelimb at level of posterior half of heart. Adult skin area on abdomen covering posterior half of heart. Fins considerably reduced. xenopus_developmental_stage climax stage NF stage